Aspects of this disclosure relate to a hybrid acoustic LC filter cascaded with a non-acoustic LC filter. The hybrid acoustic filter can filter a radio frequency signal. The hybrid acoustic LC filter can include acoustic resonators, an inductor, and a capacitor. The inductor and capacitor can be external to an acoustic resonator die. The non-acoustic LC filter includes an LC circuit. Related multiplexers, wireless communication devices, and methods are disclosed.
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2. The cascaded filter of claim 1 wherein the hybrid acoustic LC filter further includes a second inductor in parallel with the second acoustic resonator, and the second acoustic resonator is arranged as a shunt resonator in series with the inductor.
3. The cascaded filter of claim 1 wherein the first acoustic resonator and the second acoustic resonator are shunt resonators, and the capacitor and the inductor are arranged as an LC tank coupled between the first acoustic resonator and the second acoustic resonator.
4. The cascaded filter of claim 1 wherein the first acoustic resonator is coupled to a node in a signal path between the LC circuit and both the inductor and the capacitor.
5. The cascaded filter of claim 1 wherein the first acoustic resonator and the second acoustic resonator are bulk acoustic wave resonators.
This invention relates to cascaded filter systems, specifically those incorporating bulk acoustic wave resonators to address signal filtering challenges in high-frequency applications. The technology focuses on improving filter performance by using cascaded configurations of acoustic resonators, which are devices that selectively pass or block signals based on their frequency. The problem being solved involves achieving high selectivity and low insertion loss in filters, particularly for applications requiring precise frequency discrimination, such as telecommunications and signal processing. The cascaded filter system includes at least two acoustic resonators connected in series or parallel to enhance filtering capabilities. The first and second acoustic resonators in the cascade are bulk acoustic wave resonators, which operate by converting electrical signals into mechanical vibrations within a bulk material, such as piezoelectric substrates. These resonators are designed to resonate at specific frequencies, allowing them to filter out unwanted signals while passing desired frequencies with minimal loss. By cascading multiple resonators, the filter can achieve sharper roll-off and better rejection of out-of-band signals compared to single-resonator designs. The bulk acoustic wave resonators provide advantages in terms of compact size, high Q-factor, and compatibility with integrated circuit manufacturing processes. This configuration is particularly useful in applications where space constraints and performance requirements demand efficient and precise filtering solutions.
6. The cascaded filter of claim 1 wherein the LC circuit of the non-acoustic LC filter includes integrated passive devices on an integrated passive device die.
This invention relates to cascaded filter systems, specifically those incorporating non-acoustic LC (inductor-capacitor) filters with integrated passive devices. The technology addresses the need for compact, high-performance filtering solutions in electronic circuits, particularly where space constraints and signal integrity are critical. Traditional LC filters often rely on discrete components, which can be bulky and introduce parasitic effects that degrade performance. By integrating passive devices such as inductors and capacitors onto a single die, the invention reduces physical footprint, improves reliability, and enhances electrical characteristics like Q-factor and frequency response. The cascaded filter system combines multiple filter stages, where at least one stage includes an LC filter with integrated passive devices. These devices are fabricated on an integrated passive device (IPD) die, allowing for precise control over component values and minimizing parasitic inductance and capacitance. This integration improves filter performance by reducing signal distortion and insertion loss while maintaining stability across a wide frequency range. The system is particularly useful in applications requiring high-frequency filtering, such as RF (radio frequency) and microwave circuits, where traditional discrete components may not meet performance requirements. By leveraging IPD technology, the invention enables the design of compact, high-performance filters suitable for modern electronic systems, including telecommunications, automotive radar, and wireless communication devices. The use of integrated passive devices ensures consistent manufacturing quality and reduces assembly complexity compared to discrete-component designs. This approach also allows for easier
7. The cascaded filter of claim 6 wherein the inductor of the hybrid acoustic LC filter is a surface mount inductor.
8. The cascaded filter of claim 6 wherein the inductor of the hybrid acoustic LC filter includes a conductive trace of a substrate.
This invention relates to cascaded filter designs for electronic circuits, specifically addressing the challenge of integrating high-performance filtering components in compact form factors. The cascaded filter combines multiple filter stages to achieve desired frequency response characteristics, such as improved selectivity or attenuation. A key aspect is the use of a hybrid acoustic LC filter, which integrates both inductive and capacitive elements to provide efficient signal filtering. The inductor in this hybrid filter is formed using a conductive trace on a substrate, enabling miniaturization and integration with other circuit elements. This approach reduces the need for discrete inductive components, simplifying manufacturing and improving reliability. The cascaded structure allows for flexible tuning of the filter's performance by adjusting the parameters of individual stages. The conductive trace inductor provides a compact, low-loss solution for high-frequency applications, making the filter suitable for use in communication devices, signal processing systems, and other electronics requiring precise frequency filtering. The design balances performance, size, and cost, addressing limitations of traditional filter implementations.
9. The cascaded filter of claim 6 wherein the integrated passive devices include an LC shunt circuit and a series LC resonant circuit.
10. The cascaded filter of claim 1 wherein the LC circuit of the non-acoustic LC filter includes a series LC resonant circuit and an LC shunt circuit.
11. The cascaded filter of claim 10 wherein the series LC resonant circuit includes a parallel LC circuit.
12. The cascaded filter of claim 1 wherein a passband of the cascaded filter is set by the non-acoustic LC filter.
13. The cascaded filter of claim 12 wherein the first acoustic resonator is arranged to provide rejection at a frequency band outside of the passband.
This invention relates to cascaded filter designs for signal processing, particularly in radio frequency (RF) and microwave applications. The problem addressed is the need for improved frequency selectivity in filters, where unwanted signals outside the desired passband must be effectively rejected while maintaining low insertion loss within the passband. The cascaded filter includes multiple acoustic resonators arranged in series to enhance filtering performance. The first acoustic resonator in the cascade is specifically configured to reject signals at a frequency band outside the intended passband. This rejection is achieved by tuning the resonator's resonant frequency to target the unwanted frequency band, thereby attenuating those signals before they propagate through the filter. The remaining resonators in the cascade further refine the filtering characteristics, ensuring sharp roll-off and minimal distortion within the passband. The design leverages the high-Q factor of acoustic resonators to achieve precise frequency rejection without significantly impacting the passband performance. This approach is particularly useful in applications requiring strict out-of-band interference suppression, such as wireless communication systems, radar, and signal processing circuits. The cascaded structure allows for modular design, where additional resonators can be added to meet specific performance requirements. The overall filter maintains compact size and low power consumption, making it suitable for integrated circuit implementations.
14. The cascaded filter of claim 12 wherein a lower bound of the passband is at least 3 gigahertz.
A cascaded filter system is designed for high-frequency signal processing, particularly in applications requiring precise filtering of signals above 3 GHz. The system addresses the challenge of efficiently filtering high-frequency signals while maintaining signal integrity and minimizing distortion. The filter comprises multiple cascaded stages, each contributing to the overall filtering performance. Each stage includes a filter element configured to attenuate unwanted frequencies while allowing desired frequencies to pass through. The cascaded arrangement enhances the filter's selectivity and stopband attenuation, ensuring that only the target frequency range is transmitted with minimal loss. The lower bound of the passband is set at 3 GHz, ensuring that frequencies below this threshold are effectively suppressed. This design is particularly useful in telecommunications, radar systems, and other high-frequency applications where precise signal filtering is critical. The cascaded structure allows for flexibility in adjusting the filter's characteristics, such as bandwidth and attenuation levels, to meet specific application requirements. The system ensures high performance in filtering high-frequency signals while maintaining stability and reliability.
15. The cascaded filter of claim 12 wherein the passband spans from at least 3.3 gigahertz to 4.2 gigahertz.
A cascaded filter system is designed to process signals within a specific frequency range, addressing the need for precise frequency selection in high-frequency applications. The filter comprises multiple filter stages connected in series, each stage contributing to the overall filtering performance. The cascaded arrangement enhances the filter's ability to attenuate unwanted frequencies while allowing desired signals to pass through with minimal distortion. The system is particularly configured to operate within a defined passband, which spans from at least 3.3 gigahertz to 4.2 gigahertz. This frequency range is critical for applications requiring high-frequency signal processing, such as telecommunications, radar systems, and wireless communication devices. The filter's design ensures that signals within this range are transmitted with minimal loss, while frequencies outside this range are effectively suppressed. The cascaded structure allows for improved selectivity and roll-off characteristics, ensuring sharp transitions between the passband and stopband regions. This configuration is essential for maintaining signal integrity and reducing interference in high-frequency applications. The filter may also include additional components, such as impedance-matching elements or tuning mechanisms, to optimize performance across the specified frequency range. The overall system provides a robust solution for frequency filtering in demanding high-frequency environments.
17. The multiplexer of claim 16 further comprising a third filter coupled to the common node.
18. The multiplexer of claim 16 wherein the second filter includes a second hybrid acoustic LC filter.
A multiplexer system is designed to efficiently manage multiple frequency bands in wireless communication devices, addressing challenges related to signal interference and bandwidth optimization. The system includes a first filter and a second filter, each configured to process distinct frequency bands. The first filter employs a hybrid acoustic LC (inductor-capacitor) filter, combining the benefits of acoustic wave filters and LC filters to achieve high selectivity and low insertion loss. The second filter also incorporates a hybrid acoustic LC filter, tailored to handle a different frequency band than the first filter. This dual-filter architecture ensures minimal signal distortion and improved isolation between bands, enhancing overall system performance. The hybrid design leverages the precision of acoustic wave filters for sharp frequency responses and the tunability of LC filters for dynamic adjustments, making the multiplexer suitable for advanced wireless applications requiring high efficiency and reliability. The system's modular structure allows for scalable integration into various communication devices, supporting multiple frequency bands without compromising performance.
20. The wireless communication device of claim 19 wherein the wireless communication device is a mobile phone.
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December 28, 2020
November 15, 2022
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